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Defect-Enhanced CO2 Reduction Catalytic Performance in O-Terminated MXenes.
ChemSusChem ( IF 7.5 ) Pub Date : 2020-08-19 , DOI: 10.1002/cssc.202001624
Hetian Chen 1 , Albertus D Handoko 2 , Tianshuai Wang 1 , Jiale Qu 1 , Jiewen Xiao 1 , Xiaopeng Liu 1 , Dominik Legut 3 , Zhi Wei Seh 2 , Qianfan Zhang 1
Affiliation  

Electrochemical carbon dioxide reduction reaction (CO2RR) represents a promising way to generate fuels and chemical feedstock sustainably. Recently, studies have shown that two‐dimensional metal carbides and nitrides (MXenes) can be promising CO2RR electrocatalysts due to the alternating −C and −H coordination with intermediates that decouples scaling relations seen on transition metal catalysts. However, further by tuning the electronic and surface structure of MXenes it should still be possible to reach higher turnover number and selectivities. To this end, defect engineering of MXenes for electrochemical CO2RR has not been investigated to date. In this work, first‐principles modelling simulations are employed to systematically investigate CO2RR on M2XO2‐type MXenes with transition metal and carbon/nitrogen vacancies. We found that the −C‐coordinated intermediates take the form of fragments (e. g., *COOH, *CHO) whereas the −H‐coordinated intermediates form a complete molecule (e. g., *HCOOH, *H2CO). Interestingly, the fragment‐type intermediates become more strongly bound when transition‐metal vacancies are present on most MXenes, while the molecule‐type intermediates are largely unaffected, allowing the CO2RR overpotential to be tuned. The most promising defective MXene is Hf2NO2 containing Hf vacancies, with a low overpotential of 0.45 V. More importantly, through electronic structure analysis it could be observed that the Fermi level of the MXene changes significantly in the presence of vacancies, indicating that the Fermi level shift can be used as an ideal descriptor to rapidly predict the catalytic performance of defective MXenes. Such an evaluation strategy is applicable to other catalysts beyond MXenes, which could enhance high throughput screening efforts for accelerated catalyst discovery.

中文翻译:

O封端的MXene中改善缺陷的CO2还原催化性能。

电化学二氧化碳还原反应(CO 2 RR)代表了一种可持续地产生燃料和化学原料的有前途的方法。最近,研究表明,二维金属碳化物和氮化物(MXenes)可以成为有前途的CO 2 RR电催化剂,这是因为-C和-H与中间物的交替配位使过渡金属催化剂上看到的结垢关系解耦。但是,进一步通过调节MXene的电子和表面结构,仍然应该有可能达到更高的周转率和选择性。为此,迄今为止尚未研究用于电化学CO 2 RR的MXene的缺陷工程。在这项工作中,采用第一性原理建模模拟来系统地研究CO 2具有过渡金属和碳/氮空位的M 2 XO 2型MXene的RR 。我们发现,-C配位的中间体采取片段的形式(例如,* COOH,* CHO),而-H配位的中间体形成完整的分子(例如,* HCOOH,* H 2 CO)。有趣的是,当大多数MXene中存在过渡金属空位时,片段型中间体会更牢固地结合在一起,而分子型中间体在很大程度上不受影响,从而可以调节CO 2 RR的超电势。最有希望的有缺陷的MXene是Hf 2 NO 2包含Hf空位,低电势为0.45V。更重要的是,通过电子结构分析,可以观察到MXene的费米能级在空位的情况下发生显着变化,表明费米能级移位可以用作理想的描述符可以快速预测有缺陷的MXene的催化性能。这种评估策略适用于MXene以外的其他催化剂,这可以增强高通量筛选工作,以加快催化剂的发现。
更新日期:2020-08-19
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